If Usama Bin Laden (as the FBI named him) was the winner, because he hit first, he could be blamed by everyone of provoking over a decade of pain to the muslin world… and I doubt that he was so stupid (being so smart, as the CIA described him) of not knowing that attacking Americans in their own land will bring war to the Middle East and some Occidental Countries in Asia. I doubt he wanted to attack the US in US continental land.

In the other hand, if it was an internal job, those willing to attack the Middle East and bigger oil producers would have found the perfect excuse to initiate a war that in the first stages would have surrounded Iran with US forces. General Carl explain very well this last point [Video].